Describe symbolism in Confessions by Augustine of Hippo

In Book IV, we learn that one of the reasons Augustine goes to Carthage is not only to have better opportunities to study and teach rhetoric, but also to escape his hometown to avoid seeing the places where he saw and enjoyed being with his dear friend. This is shown by his comment that by God letting his friend die, the corrupt Augustine did not have a chance to corrupt his friend again after the friend is baptized. This symbolizes the power of sin and death, as opposed to the power of the connection to God, to the divine. Augustine feels overwhelmed by the power of sin and death, but later sees the power of God being displayed strongly in the incident of the death of his friend.